MOLECULAR-GENETICS AND THE INITIATION OF SOLVENTOGENESIS IN CLOSTRIDIUM-BERIJERINCKII (FORMERLY CLOSTRIDIUM-ACETOBUTYLICUM) NCIMB-8052

A physical map of the Clostridium beijerinckii (formerly Clostridium a cetobutylicum) NCIMB 8052 chromosome has been constructed, encompassin g about 90 rare restriction sites. The 14 rrn operons together with ab out 40 genes have been assigned positions on the map. Genetic analysis and gene transfer have been developed in this organism to enable in v ivo analysis of the roles of cloned genes using marker replacement tec hnology. Experiments using the available genetic tools have shown that spoOA plays a cardinal role in controlling several aspects of the tra nsition from exponential growth to stationary phase in C. beijerinckii . These include initiation of sporulation, accumulation of the storage polysaccharide, granulose, and production of acetone and butanol. Sev eral C. beijerinckii and C. acetobutylicum genes concerned with fermen tative metabolism, whose expression is modulated at the onset of solve ntogenesis, contain sequence motifs resembling OA boxes in their 5' re gulatory regions. This invites the speculation that they are under the direct control of SpoOA, and additional data are now required to test this prediction.